Pfizer vaccine provides 90 percent protection against hospitalization for six months, study finds.

The findings, which also document a waning of protection against infection, come as officials debate the necessity and timing of booster shots.

Johnson & Johnson to Seek F.D.A. Authorization for Booster Shot

The request, expected this week, comes after a study found the company’s vaccine was only 71 percent effective against hospitalization from Covid-19.

Johnson & Johnson to Seek F.D.A. Authorization for Booster Shot

The request, expected this week, comes after a study found the company’s vaccine was only 71 percent effective against hospitalization from Covid-19.

F.D.A. Panel to Weigh Pfizer Shots for Children, Boosters for Moderna and Johnson & Johnson Recipients

The timing of the meetings later this month suggests that the agency plans to move quickly to decide both issues.

Opinion | Was the Decision on Boosters Bungled?

Readers discuss the government’s handling of the issue. Also: Abortion stories; criminal justice reform; voice recognition; extinct species.

Pfizer and BioNTech Submit Data Backing Vaccine for Children 5 to 11

The companies said that their vaccine was safe and effective in that age group, and that they would submit a formal request in the coming weeks to U.S. regulators to allow a pediatric dose.

States Begin a Complex Booster Shot Rollout for Pfizer Recipients

Health officials were preparing on Friday to start giving booster shots to older and at-risk Americans, trying to make sense of new and broad eligibility guidelines.

Biden Promised to Follow the Science. But Sometimes, He Gets Ahead of the Experts.

White House officials dismiss criticism that President Biden’s comments on booster shots amount to undue pressure on public health experts.

States Begin a Complex Booster Shot Rollout for Pfizer Recipients

Health officials were preparing on Friday to start giving booster shots to older and at-risk Americans, trying to make sense of new and broad eligibility guidelines.

Biden Promised to Follow the Science. But Sometimes, He Gets Ahead of the Experts.

White House officials dismiss criticism that President Biden’s comments on booster shots amount to undue pressure on public health experts.

Federal Panel Recommends Booster Shots, Opening New Campaign Against the Virus

Scientific advisers to the C.D.C. endorsed additional doses of the Pfizer-BioNTech vaccine for older Americans but not for health care workers, in a possible rift with regulators.

Boosters for Moderna and Johnson & Johnson vaccine recipients weren’t up for debate during a C.D.C. panel.

The panel was not asked to judge whether people who received the Moderna and Johnson & Johnson vaccines should receive Pfizer-BioNTech boosters.

F.D.A. Authorizes Pfizer Booster Shots for Older and At-Risk Americans

Regulators said that people over 65 or at high risk of severe Covid-19 were eligible for an extra shot, setting up a staggered national booster campaign.

Some experts say that Biden’s new plan for donating vaccines falls short.

Of the 1.1 billion doses that the United States has committed to donations, only 300 million are expected to be shipped this year.

Moderna vs. Pfizer: Both Knockouts, but One Seems to Have the Edge

A series of studies found that the Moderna vaccine seemed to be more protective as the months passed than the Pfizer-BioNTech vaccine. Here’s why.

Pressure Grows on U.S. Companies to Share Covid Vaccine Technology

Moderna accepted $2.5 billion in taxpayer money to develop its Covid-19 vaccine. But officials in the U.S. and overseas are having trouble persuading the company to license its technology.

Covid Vaccine Prompts Strong Immune Response in Younger Children, Pfizer Says

Vaccinated kids aged 5 to 11 showed evidence of protection against the virus, the company said. The data must be reviewed by the F.D.A. before children can be inoculated.

Covid Vaccine Prompts Strong Immune Response in Younger Children, Pfizer Says

Vaccinated kids aged 5 to 11 showed evidence of protection against the virus, the company said. The data must be reviewed by the F.D.A. before children can be inoculated.

Covid Vaccine Prompts Strong Immune Response in Younger Children, Pfizer Says

Vaccinated kids aged 5 to 11 showed evidence of protection against the virus, the company said. The data must be reviewed by the F.D.A. before children can be inoculated.

F.D.A. Advisory Panel Recommends Pfizer Boosters for Older People and Others at High Risk

The committee said there was insufficient evidence to recommend third shots for all adult recipients of the vaccine, as Pfizer had requested.